Not only is 50 Hz 20% less effective in generation, it is 10-15% less efficient in transmission, it requires up to 30% larger windings and magnetic core materials in transformer construction. Electric motors are much less efficient at the lower frequency, and must also be made more robust to handle the electrical losses and the extra heat generated. Today, only a handful of countries (Peru, Ecuador, Guyana, the Philippines and South Korea) follow Tesla’s advice and use the 60 Hz frequency together with a voltage of 220-240 V. - See more at: http://www.atriumtech.com/cgi-bin/hilightcgi?Home=/home/InterWeb2000&File=/home2/searchdata/Forums/http/www.pantip.com/cafe/wahkor/topic/X3152182/X3152182.html#sthash.ZgK7Npa6.dpuf